gnutls-cli: benchmark-tls-kx can work with sub-ms accuracy

This allows micro and nanoseconds to be reported if necessary,
and it changes reporting of sample variance to standard deviation
giving a possibly better overview as it is in the same units as
the average.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

3 files changed, 33 insertions, 13 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 9e16698916..92762fa88a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -160,7 +160,7 @@ BENCHMARK_SRCS = benchmark-cipher.c benchmark.c benchmark.h benchmark-tls.c
 gnutls_cli_SOURCES = cli.c common.h common.c \
 	socket.c socket.h ocsptool-common.c inline_cmds.h \
 	$(BENCHMARK_SRCS)
-gnutls_cli_LDADD = ../lib/libgnutls.la
+gnutls_cli_LDADD = ../lib/libgnutls.la -lm
 if ENABLE_DANE
 gnutls_cli_LDADD += ../libdane/libgnutls-dane.la
 endif
diff --git a/src/benchmark-tls.c b/src/benchmark-tls.c
index 48ca7e2f0a..a9c4ce02db 100644
--- a/src/benchmark-tls.c
+++ b/src/benchmark-tls.c
@@ -349,7 +349,7 @@ static void test_ciphersuite(const char *cipher_prio, int size)
 }
 
 static
-double calc_avg(unsigned int *diffs, unsigned int diffs_size)
+double calc_avg(uint64_t *diffs, unsigned int diffs_size)
 {
 	double avg = 0;
 	unsigned int i;
@@ -363,7 +363,7 @@ double calc_avg(unsigned int *diffs, unsigned int diffs_size)
 }
 
 static
-double calc_sstdev(unsigned int *diffs, unsigned int diffs_size,
+double calc_svar(uint64_t *diffs, unsigned int diffs_size,
 		   double avg)
 {
 	double sum = 0, d;
@@ -381,7 +381,7 @@ double calc_sstdev(unsigned int *diffs, unsigned int diffs_size,
 }
 
 
-unsigned int total_diffs[32 * 1024];
+uint64_t total_diffs[32 * 1024];
 unsigned int total_diffs_size = 0;
 
 static void test_ciphersuite_kx(const char *cipher_prio, unsigned pk)
@@ -389,19 +389,18 @@ static void test_ciphersuite_kx(const char *cipher_prio, unsigned pk)
 	/* Server stuff. */
 	gnutls_anon_server_credentials_t s_anoncred;
 	gnutls_session_t server;
-	int sret, cret;
+	int sret, cret, ret;
 	const char *str;
 	char *suite = NULL;
-	/* Client stuff. */
 	gnutls_anon_client_credentials_t c_anoncred;
 	gnutls_certificate_credentials_t c_certcred, s_certcred;
 	gnutls_session_t client;
-	/* Need to enable anonymous KX specifically. */
-	int ret;
+	unsigned i;
 	struct benchmark_st st;
 	struct timespec tr_start, tr_stop;
-	double avg, sstddev;
+	double avg, svar;
 	gnutls_priority_t priority_cache;
+	const char *scale;
 
 	total_diffs_size = 0;
 
@@ -501,7 +500,7 @@ static void test_ciphersuite_kx(const char *cipher_prio, unsigned pk)
 		gnutls_deinit(client);
 		gnutls_deinit(server);
 
-		total_diffs[total_diffs_size++] = timespec_sub_ms(&tr_stop, &tr_start);
+		total_diffs[total_diffs_size++] = timespec_sub_ns(&tr_stop, &tr_start);
 		if (total_diffs_size > sizeof(total_diffs)/sizeof(total_diffs[0]))
 			abort();
 
@@ -515,10 +514,25 @@ static void test_ciphersuite_kx(const char *cipher_prio, unsigned pk)
 	gnutls_priority_deinit(priority_cache);
 
 	avg = calc_avg(total_diffs, total_diffs_size);
-	sstddev = calc_sstdev(total_diffs, total_diffs_size, avg);
 
-	printf("%32s %.2f ms, sample variance: %.2f)\n",
-	       "(avg. handshake time:", avg, sstddev);
+	if (avg < 1000) {
+		scale = "ns";
+	} else if (avg < 1000000) {
+		scale = "\u00B5s";
+		avg /= 1000;
+		for (i=0;i<total_diffs_size;i++)
+			total_diffs[i] /= 1000;
+	} else {
+		scale = "ms";
+		avg /= 1000*1000;
+		for (i=0;i<total_diffs_size;i++)
+			total_diffs[i] /= 1000*1000;
+	}
+
+	svar = calc_svar(total_diffs, total_diffs_size, avg);
+
+	printf("%32s %.2f %s, standard deviation: %.2f)\n",
+	       "(avg. handshake time:", avg, scale, sqrt(svar));
 
 	gnutls_anon_free_client_credentials(c_anoncred);
 	gnutls_anon_free_server_credentials(s_anoncred);
diff --git a/src/benchmark.h b/src/benchmark.h
index 2152e6edcf..a5e2aff124 100644
--- a/src/benchmark.h
+++ b/src/benchmark.h
@@ -71,4 +71,10 @@ timespec_sub_ms(struct timespec *a, struct timespec *b)
 	return (a->tv_sec - b->tv_sec) * 1000 + (a->tv_nsec - b->tv_nsec) / (1000 * 1000);
 }
 
+inline static unsigned long
+timespec_sub_ns(struct timespec *a, struct timespec *b)
+{
+	return (a->tv_sec - b->tv_sec) * 1000000000 + (a->tv_nsec - b->tv_nsec);
+}
+
 #endif /* GNUTLS_SRC_BENCHMARK_H */